In general, a street light is a lighting apparatus which is provided to illuminate a roadway to enhance traffic safety, and is usually supported on a lamp post. Conventional street lights adopt, e.g., a mercury lamp or a sodium lamp as a light source.
These conventional street lights using the aforementioned light source have disadvantages, such as high power consumption and short lifespan, and therefore, a novel street light using a Light Emitting Diode (LED), which exhibits remarkably low power consumption and has a nearly indefinite lifespan, has been actively studied and developed.
In current LED street lights, plural LEDs are arranged in a planar structure. However, LED street lights configured in this manner suffer from a spotlight phenomenon wherein the region immediately below the LED street light is considerably brighter than peripheral regions.
Recently, as illustrated in FIG. 1, a street light 100, in which LEDs are arranged on a curved structure 101, has been proposed. Arranging the LEDs on the curved structure 101 may somewhat increase illuminance uniformity on the surface below the street light. (in a direction to parallel to a roadway)
However, the above described LED street light has difficulty uniformly illuminating all of a plurality of lanes of a roadway because LEDs have a narrow view angle, or suffers from deterioration in lighting performance. For example, if it is assumed that the above described LED street light is installed above a two-lane road having a lane width of 3.2 m, light may be unevenly distributed in a direction perpendicular to a lane as illustrated in FIG. 2, causing severe variation in per lane illuminance.